I was recently working on getting Windows Media Services configured on a system. Going through the properties, I noticed that the "WMS Anonymous User Authentication" plugin was in an error state. On inspection, I was presented with the following dialog.
Windows Media Services
The plug-in cannot be enabled because the user name or password does not match the settings for the Windows user account used for anonymous guests.
Also, the event viewer was showing the following:
Event Type: Error
Event Source: WMServer
Event Category: Plugin
Event ID: 323
Plug-in 'WMS Anonymous User Authentication' on the server failed with the following information: Error code = 0x8007052e, Error text = 'Logon failure: unknown user name or bad password. '.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
Checking "Local Users and Groups", I could see that the specified user (WMUS_COMPNAME) certainly existed. I changed the password for the user and then set the password in the properties for "WMS Anonymous User Authentication". I was rewarded with the same message. The user name and password were correct, so I focused my attention elsewhere. I first tried changing the settings to provoke the message while running Sysinternals' Filemon and Regmon, but was unable to pull anything from the captured data that seemed like it was germane to the problem.
The next thing I tried was creating a new account and specifying that account in the properties for "WMS Anonymous User Authentication". This worked; the status of "WMS Anonymous User Authentication" became "Enabled". I found this odd, as I was working with a fresh installation of Windows Media Services. In comparing the accounts (WMUS_COMPNAME and the test account I created), I noticed the WMUS_COMPNAME account was just a member of the Guests group, while the test account was just a member of the Users group. So, I added the test account to Guests and removed it from Users, and then checked / OK'd the "WMS Anonymous User Authentication" properties. I got the aforementioned message. I changed the test account back to the original group memberships, and "WMS Anonymous User Authentication" did not complain.
At this point, I knew that the problem was related to some restriction placed on the Guests group. I ran secpol.msc to check the Local Security Policy Settings, and I noticed that Guests had been added to the Security Setting for the "Deny access to this computer from the network" policy. According to TechNet, the default for this policy is "None". Removing Guests from the setting allowed the WMUS_COMPNAME account to function as the anonymous account used by Windows Media Services.